How to replace gaz fireplace thermostat with a timer


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Old 01-21-14, 09:47 PM
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How to replace gaz fireplace thermostat with a timer

Hi,

I own a "standard" gas fireplace that is controlled with a cheap thermostat that is located in the back of the room. The control wire between the fireplace and the thermostat is brown and has white and a white wire.

To turn on my fireplace, I need to set the thermostat to "heat" and then set the desired temperature to something more than the current room temperature (I usually simply crank it to the maximum temperature), and the fireplace will heat until said temperature is achieved.

I don't like the idea of a thermostat because I don't use the fireplace to heat the room or reach a temperature, I use is because I find it nice to look at, but the more appropriate control would be to have a timer where I would set it to 5, 10, 20 or 30 minutes (or something else). This would also have the benefit that if I FORGET to turn it off, at least it will stop before the place reaches 35 celcius!!!

What would be the proper way to make sure a replacement (thermostat --> Timer). I went to the loca hardware store, but nobody seemed to have a timer that could fill this function.

Thanks.
 
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Old 01-22-14, 07:00 AM
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It sounds like you have a simple millivolt system. To turn your gas logs on all you have to do is hold the two wires at your thermostat together. Any timer switch would probably work. Since there is no electricity available at your thermostat you may need to find a timer switch that is battery or mechanically powered.

I have a switch like this to control my bathroom shower vent fan. Turning the dial mechanically winds the clock mechanism. When you turn the dial it turns on whatever you want like your fireplace and it ticks (could be a factor, so listen to it in the store before buying) down the time and clicks off. It's really simple and has been very reliable for over 11 years.
 
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Old 01-22-14, 12:24 PM
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I meant to write black and white wire, not white and white (can't find a way to edit my post).

This being said, indeed, if I short the 2 wires, the fire starts, and stops when I separate the 2 wires.

Perhaps the mechanical switch you offered would work (I don't understand why the person at the hardware store didn't offer it...), but I would prefer to AVOID the ticking since I often read in front of the fireplace.

Does an electronic timer with battery switch exists, and if so, can you point me to a picture or a link of such an object, please?

Or, even better, can I disconnect the brown wire altogether and add a gizmo that will allow me to control the fireplace with my Android phone?

Thanks
 
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Old 01-23-14, 08:08 PM
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I went to the hardware stores today, and each electronic timer seems to work on 120v. I didn't find any with a battery.

Furthermore, when I measure the voltage between the white and black wires, there is only 720mV of tension. This really is only a control wire.

I tried with a mechanical timer such the one in the picture above, and it does seem to work. But the ticking is annoying and I would prefer an electronic timer.

Can you point me to one that would work for my application?
 
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Old 01-24-14, 05:42 AM
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Here is one I found.

The 720mv you measured between your two wires sounds about right. It's also why almost any switch will work. It's extremely low voltage and current so almost any switch will work.

---

Many years from now if your stove quits working or becomes intermittent try using the manual controls on the stove. If it works by manually touching your two thermostat wires together one point of failure could be the switch. After years of use slight resistance can build in the switch from corrosion or just wearing out. For a light or furnace there is so much current that it rarely becomes an issue but with a millivolt system there is simply not much current there to begin with and it takes almost nothing to stop it or cut it down to the point to cause trouble. So in 8 or 10 years you might need a new switch or thermostat. Oddly the old fashioned mercury thermostat's seemed almost immune to this problem. One more thing we can blame on modern stuff.
 
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Old 01-24-14, 11:49 AM
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Hi,

Actually, after 1 year I had my fireplace, the thermostat started working very intermittently, which is why I started to think about alternative control. It has now been 5 years, and the thermostat really doesn't work well at all, probably related to the corrosion or wearing out problem you mentioned.

This being said, I tried to use the following timer: Home Depot GE In-Wall Digital Countdown Timer: questions, answers, how to, FAQs, tips, advice, answers, buying guide

I really like its features - fixed buttons for set times, instead of having to program it every time, but it doesn't work. When reading the manual, it says there is an internal battery, and I have to wait for 1 minute after plugging it for the battery to charge. That's 1 minute @120v AC, because when I tried it, with only the 750mv, the timer never worked, even after 15 minutes. I don't think the transformator is built for DC.. it assumes it will receive 120v AC.

How do you know that the product you proposed will work? In its specs, it talks about 12Vdc and 24v dc, but no mention of 750mV. I had seen a similar model at Home Depot, but the "associate" told me that it wouldn't work because the internal battery only server to keep the program in memory in case of power failure, but that the timer wouldn't work without 120AC.
 
 

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